Subject: [mobile-ip] MH checksum calculation (item 111?)

From: Ryuji Wakikawa <[email-masked]>
Date: Mon, 23 Sep 2002 21:03:19 +0900

Hello,
I need more clarification for MH checksum.

MH checksum calculation is explained in section 6.1.1.

         The pseudo-header contains IPv6 header fields, as specified
         in Section 8.1 of [11].  The Next Header value used in the
         pseudo-header is TBD. The addresses used in the pseudo-header
         are the addresses that appear in the Source and Destination
         Address fields in the IPv6 packet carrying the Mobility Header.
         For computing the checksum, the checksum field is set to zero.

Which address should MN use as the IP source address during MH cheksum
calculation, home address or care-of address?

regards,
ryuji

---

From: Jari Arkko <[email-masked]>
Date: Mon, 23 Sep 2002 15:17:42 +0300

> calculation, home address or care-of address?

As a part of some previously reported issues, the text has changed.
The new text is shown below. Does it explain the matter for you?

Jari
----

	16-bit unsigned integer. This field contains the checksum of
	the Mobility Header. The checksum is calculated from the octet
	string consisting of a "pseudo-header" followed by the entire
	Mobility Header starting with the Payload Proto field. The
	checksum is the 16-bit one's complement of the one's
	complement sum of this string.

	The pseudo-header contains IPv6 header fields, as specified in
	Section 8.1 of [ref]. The Next Header value used in the
	pseudo-header is TBD. The addresses used in the pseudo-header
	are the addresses that appear in the Source and Destination
	Address fields in the IPv6 packet carrying the Mobility
	Header.  The Mobility Header is considered as the upper layer
	protocol for the purposes of calculating the
	pseudo-header. The Upper-Layer Packet Length field in the
	pseudo-header MUST be set to the value of the Header Len field
	from the Mobility Header, multiplied by eight.  For computing
	the checksum, the checksum field is set to zero.

	Note that the procedures described in Section 11.2.1 apply
	even for the Mobility Header. If a Mobility Header message has
	a Home Address destination option, then the checksum
	calculation uses the home address in this option as the value of
	the IPv6 Source Address field.